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Over 1.5 million pregnancies from New York State (1959-1967) are used to study the effects of paternal age, maternal age and birth order on the risk of fetal death. The multivariate logistic function is employed to separate the intertwined effects of parental ages and birth order. The basic result that emerges from using this mathematical structure is that maternal age, paternal age, and birth order have separate, approximately equal and significant effects on the risk of a fetal death.